To answer the question whether peptide hormones are absorbed from the lower bowel, we propose to use an analogue of the peptide hormone, vasopressin, as the test material. 1-Deamino-8-D-Arginine-Vasopressin (DDAVP) is relatively inert to attack by intestingal enzymes. It will be coupled to an inert carrier, polystyrene, using an azo bond. The azo bond cannot be broken by intestingal enzymes, so the carrier and the bound peptide will pass almost unchanged to the lower small bowel and large intestine. There intestinal bacteria will split the azo bond by the action of azoreductase and liverate the peptide. Freeing of the peptide by bacteria will simulate the production of the peptide by bacteria. The peptide will either by absorbed into the blood, or be destroyed before it can be absorbed, or survive, but not be absorbed. Absorption of the peptide in significant amounts will be detected by the appearance of D-arginine-containing peptides in the blood f the experimental subject. The feces will be extracted and the extracts exained for D-arginine-containig peptides. Peptides will be separated and measured by HPLC. all steps will be tested in animals before using human subjects, but the anticipated risks are negligible. In addition to polystyrene-azo-peptide, attempts will be made to entrap vasopressin, insulin, and growth hormone in molecular capsules, which will shield the enclosed peptide against degradation in the small intestine because the pores of the capsule are too small for entry of digestive enzymes. The capsular polymer will incorporate azo bonds, which can be reduced by backterial enzymes, to open the capsual and liverate the entrapped peptide hormone. The development of such molecular capsules will permit the direct testing of the fate of these hormones in the large bowel. Capsular polymers of this kind can also be used to deliver antibiotics or anti-tumor agents to the parts of the intestine that contain bacteria.